Find & Replace

In the Query tab there is a small binocular icon (A->B, Search and replace). It doesn't find nothing (enclosed or not by single quotes). I don't even succeed to discover where it should find something (in the displayed subset of the last request?, in the current table?).
I try to correct a table where each field starts with a space (that is, I want to suppress this space). What should I enter to search: regexp ^' ', replaced by '' ? The 'Help' is of no help...